Reflection

3. surface normal same angle Reflection • Reflection off a flat surface follows a simple LAW OF REFLECTION : • angle in (incidence) equals angle out • angles measured from surface “normal” (perpendicular) exit ray incident ray

4. The real “object” (you) “image” of you Hall Mirror • It is useful to think in terms of images and objects mirror only needs to be half as high as you are tall. Your image will be twice as far from you as the mirror.

6. Refraction • Light also goes through some things • glass, water, eyeball, air • Presence of material slows light’s progress • interactions with electrical properties of atoms • Light has slowing and bending factor called the index of refraction. The denser it is the higher the index and the more it slows and bends light • glass has n = 1.52, meaning that light travels about 1.5 times slower in glass than in vacuum • water has n = 1.33 • air has n = 1.00028 • vacuum is n = 1.00000 (speed of light at full capacity)

7. The index of refraction tells how many times slower an object travels when passing into the denser substance Find the speed of light through corn oil .

8. A 1 n1 = 1.0 n2 = 1.5 2 B Refraction at a plane surface • Light bends at interface between refractive indices

9. When light goes into a denser material it bends ____________ the normal When light goes into a less dense material it bends ____________ the normal

11. Snell’s Law

12. Snell’s Law